Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. The lobes and lobules are connected by thin tubes called ducts.
Anatomy of the female breast. The nipple and areola are shown on the outside of the breast. The lymph nodes, lobes, lobules, ducts, and other parts of the inside of the breast are also shown.
Each breast also contains blood vessels and lymph vessels. The lymph vessels carry an almost colorless fluid called lymph. The lymph vessels lead to small, bean-shaped organs called lymph nodes that help the body fight infection and disease. Lymph nodes are found throughout the body. Clusters of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.
Breast cancer is sometimes detected (found) in women who are pregnant or have just given birth.
In women who are pregnant or who have just given birth, breast cancer occurs most often between the ages of 32 and 38. Breast cancer occurs about once in every 3,000 pregnancies.
Signs of breast cancer include a lump or change in the breast.
These and other signs may be caused by breast cancer or by other conditions. Check with your doctor if you have any of the following:
- A lump or thickening in or near the breast or in the underarm area.
- A change in the size or shape of the breast.
- A dimple or puckering in the skin of the breast.
- A nipple turned inward into the breast.
- Fluid, other than breast milk, from the nipple, especially if it's bloody.
- Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin that is around the nipple).
- Dimples in the breast that look like the skin of an orange, called peau d'orange.
It may be difficult to detect (find) breast cancer early in pregnant or nursing women, whose breasts are often tender and swollen.